This invention relates to a handpiece connector which cooperates with a logic circuit for controlling the operation of an ultrasonic surgical aspiration system. More particularly, this invention relates to the combination of a handpiece connector and a logic control to distinguish types of handpieces and to control differing operating frequencies for such differing handpieces. More particularly, this invention relates to a prewired handpiece connector which, when connected to a logic control circuit, provides indicator and control signals appropriate to the particular handpiece without the need for manual switching.
Devices which effectively utilize ultrasonic energy for a variety of applications are well known in a number of diverse arts. The application of ultrasonically vibrating surgical devices used to fragment and remove unwanted tissue with significant precision and safety has thus led to the development of a number of valuable surgical procedures. Accordingly, the use of ultrasonic aspirators for the fragmentation and surgical removal of tissue from a body has become well known. Initially, the technique of surgical aspiration was applied for the fragmentation and removal of cataract tissue as shown, for example, in U.S. Pat. Nos. 3,589,363 and 3,693,613. Later, such techniques were applied with significant success to neurosurgery and other surgical specialties where the application of ultrasonic energy through a small, handheld device for selectively removing tissue on a layer-by-layer basis with precise control has proven feasible.
Certain devices known in the art characteristically produce continuous vibrations having a substantially constant amplitude at a frequency of about 20 to about 30 khz up to about 40 to about 50 khz. U.S. Pat. No. 3,589,363 describes one such device which is especially adapted for use in the removal of cataracts, while U.S. Pat. No. 4,063,557 describes a device suitable for removal of soft tissue which is particularly adapted for removing highly compliant elastic tissue mixed with blood. Such devices are continuously operative when the surgeon wishes to fragment and remove tissue, and generally operate under the control of a foot switch.
Certain limitations have emerged in attempts to use such devices in a broad spectrum of surgical procedures. For example, the frequency of vibration is largely determined by the physical embodiment of a handpiece wherein standard or conventional larger handpieces are operated at a first, lower frequency and smaller microsurgical handpieces are operated at a second, higher frequency governed in large measure by physical constraints imposed on the system by the structure of a handpiece. In addition, straight or angled handpieces have been provided for the convenience of the surgeon and safety for the patient. Thus, a larger, longer handpiece is operated at a lower frequency while a smaller, shorter handpiece is operated at a higher frequency determined by the resonant systems required. In addition, the amplitude of vibration of the tips for alternative handpieces must be precisely controlled within limits. Thus, while it is desirable to control the amplitude of a larger handpiece to a first larger stroke amplitude, it is necessary when operating at a higher frequency to limit relatively the amplitude of vibration of the smaller handpiece. Thus, it is a general problem in developing instrumentation for alternative handpieces to distinguish at least between these two types of handpieces for purposes of controlling the frequency of vibration and stroke amplitude among other parameters.
A commercially available device is currently on the market and available from the assignee of this invention which incorporates major functional systems available at the handpiece for effectively removing tissue from a body. Those systems include a vibration system, an irrigation system, a suction system and a handpiece cooling system which cooperate with a control system. An ultrasonically vibrating surgical tip forms part of the handpiece and is caused to vibrate longitudinally thereby fragmenting tissue in contact with its end. In such an embodiment, the level of vibration is manually and continuously adjustable to vary the amplitude of the tip.
An ultrasonic generator provides electrical energy at ultrasonic frequencies to the handpiece and in particular to drive coils within the handpiece to control the vibrational stroke of the tip. Each of the foregoing systems and the ultrasonic generator is controlled by a control and interlock system in cooperation with the control panel. In operation, after the system itself is turned on with an appropriate switch at the control panel, vibration of the handpiece and delivery of ultrasonic energy from the ultrasonic generator to the handpiece is under the control of a foot switch operated by the surgeon. When the foot switch is depressed and the system is on, ultrasonic energy is continuously and uninterruptably provided to the tip or handpiece.
The control system for the prior art unit includes, among other features, a handpiece interlock which senses the presence of a handpiece before the control and logic systems in the units can operate. While such a system is completely effective for its intended purpose, with the development of alternatively sized handpieces requiring different frequencies, it has become a problem in the art to utilize a common control system and logic to control the operations of an instrument suitable for differing handpieces. Such a system is desirably operable without human error for the safety of the patient.
A system has been proposed which utilizes alternative connectors for differing handpieces and a manual switching arrangement to switch between the required lower and higher frequencies in accordance with the larger or smaller handpiece selected. However, the introduction of the human factor in selecting the appropriate frequency for the selected handpiece introduces the possibility of error and the possibility that a larger amplitude could be supplied to a smaller handpiece resulting in possible injury to a patient.
Accordingly, it is a general objective of this invention to provide a handpiece interlock and logic control system which is able to distinguish between at least two handpieces and provide indications of the handpiece connected to the system.
It is another object of this invention to provide a prewired handpiece which, when connected to a logic circuit according to the invention, will provide an indicator of the handpiece so connected and provide a control signal for selecting a frequency appropriate to that handpiece.
It is a further object of this invention to provide a logic circuit capable of receiving either of a pair of handpieces resonantly operable at different frequencies, to provide an indication of which of the two handpieces has been connected, and to provide a control signal indicative thereof.
It is a more general object of this invention to provide a logic circuit for sensing which of two types of handpieces has been connected for purposes of providing an indication of the connected handpiece and further controlling operating parameters in the system.
These and other objects of the invention will become apparent from the written description of the invention which follows.